Tuberous sclerosis complex (TSC) is an autosomal dominant disorder caused by mutations in tuberous sclerosis complex 1 (TSC1) or TSC2. TSC is characterized by tumors in wide range of tissues, seizures, mental retardation, autism, and organ failure. Lymphangioleiomyomatosis (LAM) is a progressive cystic lung disease affecting 35% of women with TSC and is characterized by growth of abnormal and potentially metastatic atypical smooth muscle-like LAM cells within the lungs. Sporadic LAM can develop in women without TSC, owing to somatic mutations in TSC2 gene. It has been suggested that LAM cells undergo epithelial-mesenchymal transition (EMT). Src kinases are key regulators of cellular proliferation, motility, invasiveness and EMT. The central hypothesis of this proposal is that Src is activated in LAM cells and that increased Src activation contributes to down-regulation of E-cadherin and raises the oncogenic abilities of these cells. Thus, Src inhibition represents a potential therapeutic strategy to up-regulate E-cadherin in LAM cells, suppress EMT and reduce their oncogenic and metastatic potential. The increased Src activity in TSC2-deficient cells is likely caused by inhibition of autophagy associated with hyper-activation of mTOR. Autophagy has been shown to be responsible for degradation of active Src. We propose to explore the use of Src inhibitors in LAM.